The present invention relates to a hanger, such as a casing hanger, as may be used when completing a previously drilled sub-sea well.
Frequently, when a sub-sea well has been drilled and initial investigation undertaken, the sub-sea wellhead will be blanked off and left for completion at a later date. When it is desired to complete the well, a surface wellhead is moved into position and the appropriate tubing and casing is installed between the sub-sea and surface wellheads. It is usually desirable to avoid the weight of this interconnecting tubing and casing from bearing on the sub-sea wellhead. Consequently, once the hangers have been attached to the sub-sea wellhead they are pulled in tension and tied back to the surface wellhead. The tie-back is normally achieved by inserting slips between the tubing and casing hangers and the surface wellhead.
This conventional arrangement has the serious disadvantage of requiring the interconnecting hangers, after tie-back, to be cut and dressed such that they are of the correct axial length to cooperate properly with the surface wellhead, via a pack-off assembly.